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Disassembling, repairing and maintaining a mountain bike's crankset can extend the life of the bike and improve pedaling quality. Here is a step-by-step guide to help you:

Necessary tools

  • Allen key (generally 8 mm for modern cranksets)
  • Crank puller (if necessary)
  • Crankset wrench (if cupped crankset)
  • Bearing grease
  • Cloth and bike cleaner

Steps for disassembling MTB crankset:

1. Remove the pedals  

  • Use an Allen key or pedal wrench to unscrew the pedals on each side (remember the left pedal unscrews clockwise, and the right pedal counterclockwise).
  • Disassembling, repairing and maintaining a mountain bike's crankset can extend the life of the bike and improve pedaling quality.

2. Dismantling the cranks

Depending on the model, you may need to use an Allen wrench to unscrew the center screw of the cranks. If your mtb crankset has interlocking cranks, use a crank puller to remove them.

3. Remove the crankset and bottom bracket 

If your mountain bike uses an external bottom bracket, unscrew the cups with a specific wrench. If it is a press-fit model, it may require a specific extractor. If your crankset is old, check the bearings for wear and replace them if necessary.


Repair and cleaning

1. Cleaning the parts  

Use a cloth and bicycle cleaner to clean the crankset, cranks, and bearings. Check that no parts are damaged or worn.

2. Lubrication

Apply a thin layer of grease to the bottom bracket bearings and chainring teeth. This helps reduce friction and protects against corrosion.

3. Checking the chainring teeth

Make sure the chainring teeth are not excessively worn or damaged. If they are, replace the trays.

4. Check the bearings

Spin the bearings by hand. They should spin smoothly. If you experience rubbing or hard spots, the bottom bracket may need to be replaced.

Repair and cleaning

1. Cleaning the parts  

Use a cloth and bicycle cleaner to clean the crankset, cranks, and bearings. Check that no parts are damaged or worn.

2. Lubrication

Apply a thin layer of grease to the bottom bracket bearings and chainring teeth. This helps reduce friction and protects against corrosion.

3. Checking the chainring teeth  

Make sure the chainring teeth are not excessively worn or damaged. If they are, replace the trays.

4. Check the bearings Spin the bearings by hand.

They should spin smoothly. If you experience rubbing or hard spots, the bottom bracket may need to be replaced.

Reassembly of the crankset

1. Replace the bottom bracket

Grease the threads before screwing the cups back in (if applicable), then tighten them with a wrench.

2. Reinstall the cranks

Position them correctly and tighten the crank bolts. Make sure the cranks are aligned properly.

3. Put the pedals back on

   Screw the pedals back in (always remembering the opposite directions for each side). Dismantling a carbon MTB crankset: Removing carbon MTB cranksets requires some special precautions to avoid damaging the material, which is more fragile than aluminum or steel. Here are the main precautions to follow:

Specific precautions for carbon crankset

1. Use the right tools

Carbon cranksets require the right tools to avoid creating marks or cracks. A torque wrench is recommended to ensure you apply the correct torque when reassembling.

2. Handle with care 

Carbon is sensitive to shock and excessive pressure. Avoid hitting or placing the crank on hard surfaces. Handle it gently during disassembly and maintenance.

3. Check the tightening torques</4>

When reassembling, it is crucial to respect the tightening torques specified by the manufacturer to avoid cracking the carbon. Overtightening can weaken the structure of the material and make it more vulnerable to cracking.

4. Avoid abrasive products

Use only mild, non-abrasive cleaning products to clean carbon components. Aggressive products can damage the finish and alter the resistance of the material.

5. Inspect the fasteners

Check the condition of bearings, bolts, and contact areas. Replace worn bolts or metal parts, as overtightened or oxidized screws can exert uneven pressure and damage the carbon crankset.

6. Apply a specific grease

Use a carbon-compatible grease for areas where metal parts come into contact with carbon, as it reduces the risk of galling and cracking.

Inspection after disassembly

After disassembly, carefully inspect the carbon crankset for any cracks or signs of delamination (separation of the carbon layers). If you notice any damage, have the crankset evaluated by a professional before reinstalling it.

By following these precautions, you will minimize the risk of damaging your carbon crankset and can continue to enjoy its benefits in terms of lightness and stiffness.

Maintenance tips

  • Clean and grease the crankset regularly to prevent premature wear.
  • Check the bearings every 6 months or after heavy use (mud, water, etc.).
  • If you hear crunching noises while pedaling, this may be a sign that service is needed.

This should help you maintain your crankset and optimize the performance of your mountain bike !

By regularly maintaining the crankset of your mountain bike, you not only improve the fluidity and power of your pedaling, but you also extend the life of the entire transmission system. A clean, well-lubricated crankset prevents premature wear, reduces friction noise and guarantees better performance on all terrains. Don't forget to regularly check the condition of the bearings and chainrings so you can pedal with complete peace of mind. Good maintenance makes all the difference in making the most of your mountain bike outings !